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Fix issue with newer PPC64 platforms aliasing long double to __float128 #278

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Merged
mborland merged 5 commits into from
Aug 6, 2025
Merged

Fix issue with newer PPC64 platforms aliasing long double to __float128 #278

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c27e20d
Add ppc64le macro definition for long double as alias to float128
mborland Jul 30, 2025
993cf20
Disable long double path if its the same as __float128
mborland Jul 30, 2025
9441fbd
Missing semi-colon in macro
mborland Aug 4, 2025
8a4c6b6
Make duplicated long double an unsupported type
mborland Aug 4, 2025
8fc1ee0
Replicate Debian Patch
mborland Aug 6, 2025
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14 changes: 14 additions & 0 deletions include/boost/charconv/detail/config.hpp
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Expand Up @@ -188,4 +188,18 @@ static_assert((BOOST_CHARCONV_ENDIAN_BIG_BYTE || BOOST_CHARCONV_ENDIAN_LITTLE_BY
# define BOOST_CHARCONV_HAS_BRAINFLOAT16
#endif

// Check for PPC64LE with IEEE long double (which is an alias to __float128)
// See: https://github.com/boostorg/boost/issues/1035
//
// IBM128 has 106 Mantissa Digits whereas IEEE128 has 113
// https://developers.redhat.com/articles/2023/05/16/benefits-fedora-38-long-double-transition-ppc64le#
#if (defined(__ppc64__) || defined(__PPC64__) || defined(__ppc64le__) || defined(__PPC64LE__)) && (defined(__LONG_DOUBLE_IEEE128__) || LDBL_MANT_DIG == 113)

#define BOOST_CHARCONV_LDBL_IS_FLOAT128
#define BOOST_CHARCONV_UNSUPPORTED_LONG_DOUBLE
static_assert(std::is_same<long double, __float128>::value, "__float128 should be an alias to long double. Please open an issue at: https://github.com/boostorg/charconv");

#endif


#endif // BOOST_CHARCONV_DETAIL_CONFIG_HPP
2 changes: 1 addition & 1 deletion src/from_chars.cpp
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Expand Up @@ -229,7 +229,7 @@ boost::charconv::from_chars_result boost::charconv::from_chars_erange(const char
return r;
}

#elif !defined(BOOST_CHARCONV_UNSUPPORTED_LONG_DOUBLE)
#elif !defined(BOOST_CHARCONV_UNSUPPORTED_LONG_DOUBLE) && !defined(BOOST_CHARCONV_LDBL_IS_FLOAT128)

boost::charconv::from_chars_result boost::charconv::from_chars_erange(const char* first, const char* last, long double& value, boost::charconv::chars_format fmt) noexcept
{
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2 changes: 1 addition & 1 deletion src/to_chars.cpp
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Expand Up @@ -602,7 +602,7 @@ boost::charconv::to_chars_result boost::charconv::to_chars(char* first, char* la
return boost::charconv::detail::to_chars_float_impl(first, last, static_cast<double>(value), fmt, precision);
}

#elif !defined(BOOST_CHARCONV_UNSUPPORTED_LONG_DOUBLE)
#elif !defined(BOOST_CHARCONV_UNSUPPORTED_LONG_DOUBLE) && !defined(BOOST_CHARCONV_LDBL_IS_FLOAT128)

boost::charconv::to_chars_result boost::charconv::to_chars(char* first, char* last, long double value,
boost::charconv::chars_format fmt) noexcept
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2 changes: 1 addition & 1 deletion src/to_chars_float_impl.hpp
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Expand Up @@ -770,7 +770,7 @@ to_chars_result to_chars_float_impl(char* first, char* last, Real value, chars_f
return boost::charconv::detail::to_chars_hex(first, last, value, precision);
}

#if (BOOST_CHARCONV_LDBL_BITS == 80 || BOOST_CHARCONV_LDBL_BITS == 128)
#if (BOOST_CHARCONV_LDBL_BITS == 80 || BOOST_CHARCONV_LDBL_BITS == 128) && !defined(BOOST_CHARCONV_LDBL_IS_FLOAT128)

template <>
to_chars_result to_chars_float_impl(char* first, char* last, long double value, chars_format fmt, int precision) noexcept
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